This invention relates to conveyor systems for vertically transferring articles or products from a delivery conveyor at an area where the load is to be treated or worked upon in some manner and, in particular, to such a system in which the load is separated from the delivery conveyor, transferred along a vertical transfer axis, and returned to the conveyor without displacing the load from the transfer axis.
Various automated production processes require that articles or products be transferred from a main conveyor line at stations where an operation is to be performed or articles are to be subjected to some chemical treatment, such as cleaning or the application of paint by dipping the articles in an appropriate treatment bath. Many techniques have been employed heretofore for this purpose as represented by several examples discussed below.
A conventional approach is to employ a bridge crane or a hoist suspended from overhead and manipulated by a human operator. Using this technique, the load is delivered by a conveyor in such a manner in that the bridge crane or hoist can be attached to the load and then operated to raise or lower the load through an independent path for a required process, and then either return the load to the delivery conveyor or to a subsequent processing point. Programmed bridges or programmed hoists are also employed and utilize control logic to automate the transfer function.
The essentially vertical transferring of a load may also be accomplished by the conveyor bearing the load by designing the conveyor with a capability to negotiate vertical changes in elevation. Often there is a degree of slope in the run connecting two elevations. This is referred to as continuous or synchronous conveying. A power and free conveyor may be employed.
Another means of vertically transferring a load is to utilize a section of the free rail of a power and free conveyor that can be raised or lowered. Using this approach, the load is transferred onto the shiftable section which is then raised or lowered by a secondary power means.
Other known systems include walking beam conveyors, the use of hoist mechanisms attached directly to a conveyor, "perch and free" and dual strand conveyors. All of these systems, however, have their attendant complexity and cost, and not all are suited to true vertical transferring of loads from one elevation to another.